Polymerization of (+)-Catechin in a Deep Eutectic Solvent Using a Fungal Laccase: Physicochemical Properties of the Products and Inhibition of α-Glucosidase

Deep eutectic solvents (DESs) are an alternative to traditional organic solvents for enzymatic reactions between compounds with poor solubility. Biocatalytic polymerization of the flavonoid (+)-catechin (CC) was carried out with laccase from the fungus Trametes hirsuta in a DES–buffer mixture (betaine/glycerol 60 vol %–buffer 40 vol %). The conditions for the synthesis of catechin oligomers (oligoCCs) soluble in organic solvents have been selected. According to the data from high-performance liquid chromatography, the oligoCCs had average molecular weights of 10 620 and 2540 g/mol with polydispersity indices of 1.1 and 1.09, respectively. The physicochemical properties of the obtained oligomers were studied via UV-visible, FTIR, 1 H and 13 C NMR spectroscopy. The resulting oligoCCs inhibited the α-glucosidase activity (IC 50 ~ 8 μg/mL).